Submarine eruption
Submarine eruptions are
Detection
Submarine eruptions are less studied than subaerial
Initial knowledge of these eruptions came from
Increasingly, eruptions at greater depths can be observed. For example, an explosive eruption at West Mata in Lau Basin at a depth of 1200 m was studied using submersibles.[5]
Controls on eruptive style
There is much variation in the style of submarine eruptions.[3] This changes with a number of variables including magma viscosity, water depth, effusion rate and volatile content.[2] Many studies highlight the effects of pressure which increases with depth. It is believed that increased pressure restricts the release of volatile gases, resulting in effusive eruptions.[6] This is not to say that explosive eruptions do not occur at depth, just that a higher volatile content is required. It has been estimated that at 500 m explosive activity associated with basalts is suppressed, while depths greater than 2300 m would be sufficient to prevent the majority of explosive activity from rhyolite lava.[1]
Shallow water eruptions
At shallow depths it is common for submarine eruptions to be explosive due to the reaction between volatiles in the magma and water which generates a significant quantity of steam.[7] These eruptions described as Surtseyan are characterised by large quantities of steam and gas and creating large amounts of pumice.[8] This activity has occurred in many locations. An example is Fukuto-Okanoba near Japan. This activity has been observed for almost a century and causes discoloured water, jets of steam and ash, and pumice is found floating in the surrounding water.[9]
Shallow eruptions can lead to the creation of islands. The most well known is Surtsey in Iceland (1963-1967).[10] Similar island building activity occurs frequently but these are often short lived.[10]
Volatile content is also significant. Magma being transported into the ocean through tunnels may see gases being exsolved before reaching the water and so the eruption is effusive. This has been seen in Hawaii.
Deep water eruption
With increased depth there is greater pressure and it is believed that this results in effusive eruptions.
Two formations associated with submarine eruptions are
See also
References
- ^ a b Parfitt, L. and Wilson, L. (2008) Fundamentals of Physical Volcanology, Blackwell Publishing.
- ^ a b Fagents, S.A., Gregg, T.K.P. and Lopes, R.M.C. (2013) Modelling Volcanic processes: the Physics and Mathematics of Volcanism, Cambridge University Press, UK.
- ^ a b c d e Rubin, K.H., Soule, S.A., Chadwick, W.W., Farnan. D.J., Clague, A.A., Emberley. R.W., Baker, E.T., Perfit, M.R., Caress, D.W. and Dziak, R.P. (2012) Volcanic eruptions in the deep sea, Oceanography, 25(1): 142-157.
- ^ a b [1], NOAA (2013) Recent Submarine Volcanic Eruptions.
- ^ [2], Livescience (2011) Explosive Underwater Eruptions Are Deepest Yet Seen
- ^ Fransis, P. (1993) Volcanoes: A Planetary Perspective, Oxford University Press.
- ^ Head, J.W. and Wilson, L. (2008) Deep submarine pyroclastic eruptions: theory and predicted landforms and deposits, Journal of Volcanology and Geothermal Research, 121: 155-193.
- ^ [3], Smithsonian Institution National Museum of Natural History Global Volcanism Program (2013).
- ^ [4], Volcano Discovery (2013) Fukutoku-Okanoba volcano.
- ^ a b Siebert, L., Simkin, T. and Kimberley, P. (2010) Volcanoes of the World, University of California Press.
- ^ a b c Decker, R. and Decker, B. (1989) Volcanoes, W.H. Freeman and Company, USA.
- ISSN 0016-7606.
- ^ Wright, I.C. and Gamble, J.A. (1999) Southern Kermadec Submarine caldera arc volcanoes (South West Pacific): caldera formation by effusive and pyroclastic eruption, Marine Geology, 161:207-277